There are known many types of tamper-proof sealing means used in containers housing valuables or in structures where security is important. In one type of security means, the lock comprises two members adapted for automatic interlocking engagement on the introduction of one member into a cavity of the other member. The first member generally is a rod shaped body with a tapered insertion end and with an abruptly restricted cross-sectional area slightly rearward of the tapered section to form a shoulder. Single engagement locks of this type are disclosed in U.S. Pat. Nos. 3,730,578 and 1,553,188.
In the single lock ring engagement disclosed in U.S. Pat. No. 3,730,578 the second member is a block with throughgoing openings, the diameter of which is smaller at the end where the rod shaped body is introduced than at the opposite end. This opposite end is closed by an inserted sleeve provided with a bore facing the interior of the block and of the same diameter as the smallest diameter of the throughgoing openings. Such a single lock is used partly as a padlock but specifically as a seal, for instance, on containers for transport of goods. The opening of the lock requires the use of force and the fact that the lock is intact should indicate that no unauthorized person has had access to the interior of the container.
However, it was found that a lock of this type could be opened and relocked without leaving any direct signs of the use of force and thus the security in this type system would be lost. Furthermore, the interlocking of the two members was not very secure because the lock could be opened by impact or by means of a crowbar. In the single engagement lock disclosed in U.S. Pat. No. 1,553,188 the aforesaid lock ring is replaced by a tubular sleeve open at both ends. Theoretically, this results in an improved interlocking connection between the two members of the lock; this lock can also be broken by a relatively simple operation since the block member consists of porcelain or plastic material.
There are also disclosed in the prior art various other fasteners or security devices wherein the locking connector is of the type which has two similar elements that are interlocked together. It may be desirable in this type of security system that the connector not be releasable because of the desired permanency of the connection being made. A connector that cannot be released except by obvious destruction would provide such a seal. The use of such destructible seals can be effective in reducing tampering or the theft of the contents of a container. Such a connector would probably not, however, provide ultimate security for the reason that it is preferably made of plastic-like material that could be relatively easily cut and replaced. This type of security device is disclosed in U.S. Pat. No. 3,897,162.
Previous construction of security seals or other types of devices in many instances consists of expensive components that are also difficult to use. Some of these seals or devices require expensive tools in order that they can be appropriately installed or closed; these devices also do not totally eliminate the possibility of undesired tampering or manipulation. Another known construction involves the use of a metal strip drawn through the opening or openings of an article which is to be sealed. After the sheet metal strip is flexed over upon itself, it can be riveted at both of its ends by tongs or pliers. The rivet location is subsequently covered with a plastic cap. With this construction seal, there is the drawback that riveting of the metal strip is not undertaken in a completely faultless manner.
Tampering or manipulation for the purposes of providing a false seal or giving the appearance that the article has in fact been sealed is possible. Also known is a system which involves a seal whereby both ends of a flexible strip are associated with rather bulky closure elements. Thus, this construction of seal cannot be employed in those instances in which the opening or openings of the article to be sealed is small, especially in conjunction with openings for the use of convenient closing devices such as screws and the like. Alsothese devices are generally difficult to install or expensive for volume use. While these seals do provide assurance that unauthorized openings have not occurred, such seals can generally be circumvented. This is done by anyone having access to a supply of seals by simply replacing a broken seal with a new one.
Counterfeiting seals also would not be difficult for someone willing to go through the considerable time and expense involved. These prior art devices which utilize a frangible or destructible device have been described in various patents, for example Dutch patent application 7,412,131 or U.S. Pat. Nos. 2,142,048; 3,983,645 and 3,924,800. Devices like these are used for dispatching documents in transportation bags. One such device takes the form of a flat envelope having along one of the edges a zip fastener which in closed position is sealed by means of a rupturable or frangible sealing member.
In order to be able to establish afterwards that the transportation bag has been opened by a person authorized to do so, one must be able to ascertain if the seal is original or a replacement. With such a sealing device, it would be possible to reapply the sealing member quickly and without the use of aids, thus giving the impression that the sealing member was never broken. In the Dutch patent above noted, the elastic means which are to be deformed are formed by resilient lips projecting from the shaft portion of the sealing member. In the head of the sealing member, there is formed a slit wherein a special tool can be engaged for twisting said sealing member in order to break it. It is obvious, however, that in addition to being complex, a design such as this leads to a relatively high cost for the manufacture of this sealing member, especially upon volume and continued use.
U.S. patent application Ser. No. 4,478,443 discloses a postage meter security seal. In this apparatus, the sealing apparatus includes a cover with a cut-out portion. The cover includes two cover tab receiving openings which are positioned diametrically across from each other. The center of the cut-out portion has a bore hold that runs completely through the thickness of the cover. An insert is provided which is adapted to fit into and mate with the bore hole. The insert contains an opening which will accept a screw and also contains upwardly extending tabs. A screw is used to fasten the sealing apparatus to the postage meter. When the tabs are stacked over the screw, it is impossible to remove the screw without first breaking off the tabs. A broken tab will thus indicate that the meter has been tampered with.
This security seal device does work in an exemplary fashion for its intended purpose, but there are some problems in its use. The security seal of this invention can be difficult to manufacture in that the tab receiving portions must be welded over utilizing a special tool to produce the desired result. Often times an unskilled operator will have a difficult time performing the operation of welding the tab portions over the screw. In addition, the tooling to perform the welding operation is relatively complex and therefore relatively expensive in that it must fit into the bore hole in a certain pattern to affect the welding operation of the tabs. It is also well know that the expensive tooling will wear after repeated use and, therefore, have to be replaced. Accordingly, the postage meter security seal disclosed in the above-mentioned patent does have some disadvantages that can cause some problems in high volume manufacturing applications.
There is thus a need to provide a simple and relatively inexpensive sealing device of the type that will be described herein in which no complex or expensive tools are required to manufacture the sealing member.